The pharmacokinetics of intravenously administered gadopentetate dimeglumine in normal subjects conforms to a two compartment open-model with mean distribution and elimination half-lives (reported as mean ± SD) of about 0.2 ± 0.13 hours and 1.6 ± 0.13 hours, respectively.
Upon injection, the meglumine salt is completely dissociated from the gadopentetate dimeglumine complex. Gadopentetate is exclusively eliminated in the urine with 83 ± 14% (mean ± SD) of the dose excreted within 6 hours and 91 ± 13% (mean ± SD) by 24 hours, post-injection.
The renal and plasma clearance rates (1.76 ± 0.39 mL/min/kg and 1.94 ± 0.28 mL/min/kg, respectively) of gadopentetate are essentially identical, indicating no alteration in elimination kinetics on passage through the kidneys and that the drug is essentially cleared through the kidney. The volume of distribution (266 ± 43 mL/kg) is equal to that of extracellular water and clearance is similar to that of substances which are subject to glomerular filtration. Following GBCA administration, gadolinium is present for months or years in brain, bone, skin, and other organs [see Warnings and Precautions (5.3)]
In vitro laboratory results indicate that gadopentetate does not bind to human plasma protein. In vivo protein binding studies have not been done.
Magnevist is excreted via the kidneys, even in patients with impaired renal function. In patients with impaired renal function, the serum half-life of gadopentetate dimeglumine is prolonged. Mean serum elimination half-lives of a single intravenous dose of gadopentetate dimeglumine (0.1 mmol/kg) were 2.6 ± 1.2 h, 4.2 ± 2.0 h and 10.8 ± 6.9 h, for mildly (creatinine clearance, CLCR = 60 to < 90 mL/min), moderately (CLCR = 30 to < 60 mL/min) and severely (CLCR = < 30 mL/min) impaired patients, respectively, as compared with 1.6 ± 0.1 h in healthy subjects.
Long-term animal studies have not been performed to evaluate the carcinogenic potential of gadopentetate dimeglumine.
A comprehensive battery of in vitro and in vivo studies in bacterial and mammalian systems suggest that gadopentetate dimeglumine is not mutagenic or clastogenic and does not induce unscheduled DNA repair in rat hepatocytes or cause cellular transformation of mouse embryo fibroblasts. However, the drug did show some evidence of mutagenic potential in vivo in the mouse dominant lethal assay at doses of 6 mmol/kg, but did not show any such potential in the mouse and dog micronucleus tests at intravenous doses of 9 mmol/kg and 2.5 mmol/kg, respectively.
When administered intra-peritoneally to male and female rats daily prior to mating, during mating, and during embryonic development for up to 74 days (males) or 35 days (females), gadopentetate caused a decrease in number of corpora lutea at the 0.1 mmol/kg dose level. After daily dosing with 2.5 mmol/kg suppression of food consumption and body weight gain (males and females) and a decrease in the weights of testes and epididymis were observed.
Intravenous injections of gadopentetate dimeglumine (16 to 18 doses over 23 to 25 days) caused spermatogenic cell atrophy and degeneration in male rats at a dose of 5 mmol per kg; 8 times (based on body surface area [BSA]) the recommended human dose.
Spermatogenesis was not affected in rats and dogs given repeatedly over 4 weeks at a dose of 2.5 mmol per kg or 4 times based on BSA (rats) and 14 times based on BSA (dogs) the recommended human dose.
Magnevist injection was administered to 1272 patients in open label controlled clinical studies. The mean age of these patients was 46.4 years (range 2 to 93 years). Of these patients, 55% (700) were male and 45% (572) were female. Of the 1271 patients who received Magnevist injection and for whom race was reported, 82.1% (1043) were Caucasian, 9.7% (123) were Black, 5.3% (67) were Hispanic, 2.1% (27) were Oriental/Asian, and 0.9% (11) were other. Of the 1272 patients, 550 patients were evaluated in blinded reader studies. These evaluated the use of contrast enhancement in magnetic resonance imaging of lesions in the head and neck, brain, spine and associated tissues, and body (excluding the heart). Of the 550 patients, all patients had a reason for an MRI and efficacy assessments were based on pre-and post- Magnevist injection film quality, film contrast, lesion configuration (border, size, and location), and the number of lesions. The protocols did not include systematic verification of specific diseases or histopathologic confirmation of findings.
Of the above 550 patients, 97 patients received 0.1 mmol/kg Magnevist injection IV in two clinical trials of Magnevist MRI contrast enhancement for body imaging. Of these 97, 68 had MRIs of the internal organs/structures of the abdomen or thorax (excluding the heart); 8 had breast images and 22 had images of appendages. The results of MRIs before and after Magnevist use were compared blindly. Overall additional lesions were identified in 22/97 (23%) of the patients after Magnevist injection. The mean number of lesions identified before (1.49/patient) and after Magnevist (1.75/patient) were similar. Seven (8%) of the patients had lesions seen before Magnevist that were not seen after Gadopentetate dimeglumine. Overall, after Magnevist injection, 41% of the images had a higher contrast score than before injection; and 18% of the images had a higher contrast score before Magnevist injection than after Magnevist injection. Magnevist MRI of the 8 patients with breast images were not systematically compared to the results to mammography, breast biopsy or other modalities. In the 22 patients with appendage images (e.g., muscle, bone and intraarticular structures), Magnevist MRI was not systematically evaluated to determine the effects of contrast biodistribution in these different areas.
Of the above 550 patients, 66 patients received Magnevist 0.1 mmol/kg IV in clinical trials of Magnevist MRl contrast enhancement of lesions in the head and neck. A total of 66 MRI images were evaluated blindly by comparing each pair of MRI images, before and after Magnevist injection. In these paired images, 56/66 (85%) had greater enhancement after Magnevist and 40/66 (61%) had better lesion configuration or border delineation after Gadopentetate dimeglumine. Overall, there was better contrast after Magnevist in 55% of the images, comparable enhancement in 44 (36%) before and after Gadopentetate dimeglumine, and better enhancement in 9% without Gadopentetate dimeglumine.
In the studies of the brain and spinal cord, Magnevist 0.1 mmol/kg IV provided contrast enhancement in lesions with an abnormal blood brain barrier.
In two studies, a total of 108 patients were evaluated to compare the dose response effects of 0.1 mmol/kg and 0.3 mmol/kg of Magnevist in CNS MRI. Both dosing regimens had similar imaging and general safety profiles; however, the 0.3 mmol/kg dose did not provide additional benefit to the final diagnosis (defined as number of lesions, location, and characterization).
Magnevist injection is a clear, colorless to slightly yellow solution containing 469.01 mg/mL of gadopentetate dimeglumine. Magnevist injection is supplied in the following sizes:
- 5 mL single-dose vials, rubber stoppered, in individual cartons of 10, 2 cartons per Box NDC 50419-188-81
- 10 mL single-dose vials, rubber stoppered, in individual cartons of 10, 2 cartons per Box NDC 50419-188-82
- 15 mL single-dose vials, rubber stoppered, in individual cartons of 10, 2 cartons per Box NDC 50419-188-83
- 20 mL single-dose vials, rubber stoppered, in individual cartons of 10, 2 cartons per Box NDC 50419-188-84
Single-Dose Pre-Filled Syringes
- 10 mL pre-filled disposable syringe, Boxes of 5 NDC 50419-188-36
- 15 mL pre-filled disposable syringe, Boxes of 5 NDC 50419-188-37
- 20 mL pre-filled disposable syringe, Boxes of 5 NDC 50419-188-38
Magnevist injection should be stored at controlled room temperature, between 15 — 30° C (59 — 86° F) and protected from light. DO NOT FREEZE. Should freezing occur in the vial, Magnevist injection should be brought to room temperature before use. If allowed to stand at room temperature for a minimum of 90 minutes, Magnevist injection should return to a clear, colorless to slightly yellow solution. Before use, examine the product to assure that all solids are redissolved and that the container and closure have not been damaged. Should solids persist, discard vial.
- Advise the patient to read the FDA-approved patient labeling (Medication Guide).
Nephrogenic Systemic Fibrosis
GBCAs increase the risk of NSF among patients with impaired elimination of drugs. To counsel patients at risk of NSF:
- Describe the clinical manifestations of NSF
- Describe procedures to screen for the detection of renal impairment
Instruct the patients to contact their physician if they develop signs or symptoms of NSF following Magnevist administration, such as burning, itching, swelling, scaling, hardening and tightening of the skin; red or dark patches on the skin; stiffness in joints with trouble moving, bending or straightening the arms, hands, legs or feet; pain in the hip bones or ribs; or muscle weakness.
- Advise patients that gadolinium is retained for months or years in brain, bone, skin, and other organs in patients with normal renal function. The clinical consequences of retention are unknown. Retention depends on multiple factors and is greater following administration of linear GBCAs than following administration of macrocyclic GBCAs [see Warnings and Precautions (5.3)].
© 1988, Bayer HealthCare Pharmaceuticals Inc. All rights reserved.
Bayer HealthCare Pharmaceuticals Inc.
Whippany, NJ 07981
Manufactured in Germany
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